US20050036934A1 - Method of making submicron cemented carbide - Google Patents
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- US20050036934A1 US20050036934A1 US10/833,187 US83318704A US2005036934A1 US 20050036934 A1 US20050036934 A1 US 20050036934A1 US 83318704 A US83318704 A US 83318704A US 2005036934 A1 US2005036934 A1 US 2005036934A1
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 6
- 239000000843 powder Substances 0.000 claims abstract description 37
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 12
- 239000012298 atmosphere Substances 0.000 claims abstract description 11
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052751 metal Inorganic materials 0.000 claims abstract description 9
- 239000002184 metal Substances 0.000 claims abstract description 9
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 9
- 150000001875 compounds Chemical class 0.000 claims abstract description 7
- 150000003839 salts Chemical class 0.000 claims abstract description 7
- 239000002904 solvent Substances 0.000 claims abstract description 5
- 230000000737 periodic effect Effects 0.000 claims abstract description 4
- 239000002798 polar solvent Substances 0.000 claims abstract description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 3
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 3
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000011651 chromium Substances 0.000 claims description 13
- PHFQLYPOURZARY-UHFFFAOYSA-N chromium trinitrate Chemical group [Cr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PHFQLYPOURZARY-UHFFFAOYSA-N 0.000 claims description 12
- 238000005255 carburizing Methods 0.000 claims description 4
- 238000001704 evaporation Methods 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229910003206 NH4VO3 Inorganic materials 0.000 claims description 3
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims description 3
- 238000010000 carbonizing Methods 0.000 claims description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 17
- 229910052739 hydrogen Inorganic materials 0.000 description 12
- 239000001257 hydrogen Substances 0.000 description 12
- 238000003801 milling Methods 0.000 description 12
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten(VI) oxide Inorganic materials O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 11
- 238000009826 distribution Methods 0.000 description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 5
- 239000011230 binding agent Substances 0.000 description 5
- 239000006229 carbon black Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 229910009043 WC-Co Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 239000003966 growth inhibitor Substances 0.000 description 3
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- BFGKITSFLPAWGI-UHFFFAOYSA-N chromium(3+) Chemical compound [Cr+3] BFGKITSFLPAWGI-UHFFFAOYSA-N 0.000 description 2
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 229940117975 chromium trioxide Drugs 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000011363 dried mixture Substances 0.000 description 1
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
- C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
- C22C1/053—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor with in situ formation of hard compounds
- C22C1/055—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor with in situ formation of hard compounds using carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
Definitions
- the present invention relates to a method of making submicron cemented carbide with extremely narrow grain size distribution.
- Cemented carbide inserts with a grain refined structure are today used to a great extent for machining of steel, stainless steels and heat resistant alloys in applications with high demands on both toughness and wear resistance. Another important application is in micro drills for the machining of printed circuit board so called PCB-drills.
- Common grain growth inhibitors include vanadium, chromium, tantalum, niobium and/or titanium or compounds involving these elements. When added, generally as carbides, they limit grain growth during sintering, but they also have undesirable side effects, affecting the toughness behavior in an unfavorable direction. Additions of vanadium or chromium are particularly detrimental and have to be kept on a very low level in order to limit their negative influence on the sintering behavior. Both vanadium and chromium reduce the sintering activity often resulting in an uneven binder phase distribution and toughness reducing defects in the sintered structure. Large additions are also known to result in precipitation of embrittling phases in the WC/Co grain boundaries. According to WO 99/13120, the amount of grain growth inhibitors can be reduced if a carbon content of the cemented carbide close to eta-phase formation is chosen.
- Grain growth inhibitors limit the grain growth during sintering. However, since they generally are introduced in powder form their distribution is not as even as desirable. As a result in the sintered structure there often appear areas with abnormal grains of WC. A solution to this problem is disclosed in U.S. Pat. No. 5,993,730 according to which the WC grains are coated with Cr prior to the mixing operation. In this way the number of areas with abnormal grain growth can be reduced. However, larger grains from the original powder still remain in the sintered structure. The grains result from grain growth during the carburization operation. A solution to the problem is disclosed in JP-A-10-212165 in which tungsten oxide powder is mixed with powder of chromium oxide or chromium metal, reduced in hydrogen mixed with carbon powder and carburized to WC. Again because of the uneven distribution of the chromium a certain grain growth during carburization can not be avoided.
- tungsten carbide powder comprising dissolving at least one organic or inorganic metal salt or compound of at least one of the groups IV, V, and VI of the periodic system in at least one polar solvent, adding WO 3 powder to the solution, evaporating the solvent, heat treating the remaining powder in a reducing atmosphere, mixing the obtained powder with carbon and carburizing.
- FIG. 1 illustrates in about 4000 ⁇ a typical microstructure of a WC-Co cemented carbide made with a WC-powder produced according to the invention.
- FIGS. 2 and 3 illustrates in about 4000 ⁇ a typical microstructure of the same cemented carbide grade produced from WC-powder according to prior art.
- one or more organic or inorganic metal salts or compounds of at least one of the groups IV, V and VI of the periodic system particularly Cr, V, Mo, W, most preferably Cr and V are dissolved in at least one polar solvent such as ethanol, methanol and water.
- Powder of WO 3 is added to the solution. The solvent is evaporated and remaining powder is heat treated in reducing atmosphere, mixed with carbon and carburized to WC with a narrow grain size distribution.
- a coated hard constituent WC powder is obtained, which after addition of pressing agent alone or optionally with other coated hard constituent powders and/or binder phase metals can be compacted and sintered according to standard practice.
- chromium (III)nitrate 9-hydrate, (Cr(NO 3 ) 3 ⁇ 9H 2 O) or ammonium vanadate (NH 4 VO 3 ), is dissolved in a suitable solvent such as 10% water and 90% ethanol (C 2 H 5 OH).
- WO 3 is added to the solution under stirring and dried in an evaporator. The dried mixture is reduced to W-metal in hydrogen, mixed with carbon and carburized to WC.
- a submicron WC-10% Co-0.4% Cr cemented carbide was made in the following way according to the invention: 56.5 g chromium (III)nitrate-9-hydrate (Cr(NO 3 ) 3 ⁇ 9H 2 O) was dissolved in 100 ml water and 900 ml ethanol (C 2 H 5 OH). To this solution was added 2000 g tungsten trioxide (WO 3 ). The milling was carried out in a 2.4 litre ball mill with 2000 g milling balls and the milling time was 120 minutes. The mixture was heated up in vacuum and the temperature was increased to about 70° C. Careful stirring took place continuously during the time the water-ethanol solution was evaporating until the mixture had become dry.
- the powder obtained was fired in a continuos laboratory reduction furnace in a porous bed about 2 mm thick in dry hydrogen atmosphere (dew point ⁇ 60° C.), heating rate about 30° C./min, reduction in hydrogen for 115 minutes at 700° C. completed by further reduction for 115 minutes at 900° C., finally followed by cooling in hydrogen atmosphere at about 30° C./min.
- the tungsten powder obtained was mixed with carbon black to over-stoichiometric composition (6.25 weight-% C) and homogenized in a 2.4 litre ball mill. Ratio milling balls to powder weight: 1/1. Milling time: 180 min. The powder mixture was burnt off in hydrogen atmosphere in a laboratory carburizing furnace at 1350° C. for 150 minutes. Heating rate: 30° C./min and cooling rate: 45° C./min.
- the powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys.
- a submicron microstructure with a narrow grain size distribution as illustrated in FIG. 1 was obtained.
- the powder obtained was fired in a furnace in a porous bed about 1 cm thick in nitrogen atmosphere in a closed vessel, heating rate 10° C./min to 550° C., completed with reduction in hydrogen for 90 minutes, finally followed by cooling in hydrogen atmosphere at 10° C./min. No cooling step between burning off and reduction step was used.
- the powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys.
- Co-binder Co-powder extra fine
- carbon content carbon black
- a submicron microstructure with about the same mean grain size but a somewhat broader grain size distribution compared to FIG. 1 as illustrated in FIG. 2 was obtained.
- a WC-10% Co-0.4% Cr cemented carbide was made in the following way according to JP-A-10-212165: 2.7 g chromium trioxide (Cr 2 O 3 ) was mixed up with 500 g tungsten trioxide (WO 3 ). The mixing was carried out in a 2.4 litre ball mill with 500 g milling balls and the milling time was 120 minutes.
- the powder mixture was fired in a continues laboratory reduction furnace in a porous bed about 2 mm thick in dry hydrogen atmosphere (dew point ⁇ 60° C.), heating rate about 30° C./min, reduction in hydrogen for 115 minutes at 700° C. completed by further reduction for 115 minutes at 900° C., finally followed by cooling in hydrogen atmosphere at about 30° C./min.
- the tungsten powder obtained was mixed with carbon black to over-stoichiometric composition (6.25 weight-% C) and homogenized in a 2.4 litre ball mill. Ratio milling balls to powder weight: 1/1.
- Milling time 180 min.
- the powder mixture was burnt off in hydrogen atmosphere in a laboratory carburizing furnace at 1350° C. for 150 minutes. Heating rate: 30° C./min and cooling rate: 45° C./min.
- the powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys.
- a submicron microstructure with about the same mean grain size but broader grain size distribution compared to FIGS. 1 to 2 as illustrated in FIG. 3 was obtained.
Abstract
Description
- The present invention relates to a method of making submicron cemented carbide with extremely narrow grain size distribution.
- Cemented carbide inserts with a grain refined structure are today used to a great extent for machining of steel, stainless steels and heat resistant alloys in applications with high demands on both toughness and wear resistance. Another important application is in micro drills for the machining of printed circuit board so called PCB-drills.
- Common grain growth inhibitors include vanadium, chromium, tantalum, niobium and/or titanium or compounds involving these elements. When added, generally as carbides, they limit grain growth during sintering, but they also have undesirable side effects, affecting the toughness behavior in an unfavorable direction. Additions of vanadium or chromium are particularly detrimental and have to be kept on a very low level in order to limit their negative influence on the sintering behavior. Both vanadium and chromium reduce the sintering activity often resulting in an uneven binder phase distribution and toughness reducing defects in the sintered structure. Large additions are also known to result in precipitation of embrittling phases in the WC/Co grain boundaries. According to WO 99/13120, the amount of grain growth inhibitors can be reduced if a carbon content of the cemented carbide close to eta-phase formation is chosen.
- Grain growth inhibitors limit the grain growth during sintering. However, since they generally are introduced in powder form their distribution is not as even as desirable. As a result in the sintered structure there often appear areas with abnormal grains of WC. A solution to this problem is disclosed in U.S. Pat. No. 5,993,730 according to which the WC grains are coated with Cr prior to the mixing operation. In this way the number of areas with abnormal grain growth can be reduced. However, larger grains from the original powder still remain in the sintered structure. The grains result from grain growth during the carburization operation. A solution to the problem is disclosed in JP-A-10-212165 in which tungsten oxide powder is mixed with powder of chromium oxide or chromium metal, reduced in hydrogen mixed with carbon powder and carburized to WC. Again because of the uneven distribution of the chromium a certain grain growth during carburization can not be avoided.
- It is an object of the present invention to avoid or alleviate the problems of the prior art.
- It is further an object of the present invention to provide a method of making a WC-powder with an extremely narrow grain size distribution.
- There is provided a method of making tungsten carbide powder comprising dissolving at least one organic or inorganic metal salt or compound of at least one of the groups IV, V, and VI of the periodic system in at least one polar solvent, adding WO3 powder to the solution, evaporating the solvent, heat treating the remaining powder in a reducing atmosphere, mixing the obtained powder with carbon and carburizing.
-
FIG. 1 illustrates in about 4000×a typical microstructure of a WC-Co cemented carbide made with a WC-powder produced according to the invention. -
FIGS. 2 and 3 illustrates in about 4000× a typical microstructure of the same cemented carbide grade produced from WC-powder according to prior art. - It has now surprisingly been found that a WC-powder with an extremely narrow grain size distribution can be obtained if the WO3-powder is coated with Cr prior to reduction and carburization.
- According to the method of the present invention one or more organic or inorganic metal salts or compounds of at least one of the groups IV, V and VI of the periodic system particularly Cr, V, Mo, W, most preferably Cr and V are dissolved in at least one polar solvent such as ethanol, methanol and water. Powder of WO3 is added to the solution. The solvent is evaporated and remaining powder is heat treated in reducing atmosphere, mixed with carbon and carburized to WC with a narrow grain size distribution. As a result a coated hard constituent WC powder is obtained, which after addition of pressing agent alone or optionally with other coated hard constituent powders and/or binder phase metals can be compacted and sintered according to standard practice.
- In a preferred embodiment, chromium (III)nitrate 9-hydrate, (Cr(NO3)3×9H2O) or ammonium vanadate (NH4VO3), is dissolved in a suitable solvent such as 10% water and 90% ethanol (C2H5OH). WO3 is added to the solution under stirring and dried in an evaporator. The dried mixture is reduced to W-metal in hydrogen, mixed with carbon and carburized to WC.
- The invention is additionally illustrated in connection with the following Examples, which are to be considered as illustrative of the present invention. It should be understood, however, that the invention is not limited to the specific details of the Examples.
- A submicron WC-10% Co-0.4% Cr cemented carbide was made in the following way according to the invention: 56.5 g chromium (III)nitrate-9-hydrate (Cr(NO3)3×9H2O) was dissolved in 100 ml water and 900 ml ethanol (C2H5OH). To this solution was added 2000 g tungsten trioxide (WO3). The milling was carried out in a 2.4 litre ball mill with 2000 g milling balls and the milling time was 120 minutes. The mixture was heated up in vacuum and the temperature was increased to about 70° C. Careful stirring took place continuously during the time the water-ethanol solution was evaporating until the mixture had become dry.
- The powder obtained was fired in a continuos laboratory reduction furnace in a porous bed about 2 mm thick in dry hydrogen atmosphere (dew point <−60° C.), heating rate about 30° C./min, reduction in hydrogen for 115 minutes at 700° C. completed by further reduction for 115 minutes at 900° C., finally followed by cooling in hydrogen atmosphere at about 30° C./min.
- The tungsten powder obtained was mixed with carbon black to over-stoichiometric composition (6.25 weight-% C) and homogenized in a 2.4 litre ball mill. Ratio milling balls to powder weight: 1/1. Milling time: 180 min. The powder mixture was burnt off in hydrogen atmosphere in a laboratory carburizing furnace at 1350° C. for 150 minutes. Heating rate: 30° C./min and cooling rate: 45° C./min.
- The powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys. A dense cemented carbide structure with porosity AOO and hardness HV3=1665 was obtained. A submicron microstructure with a narrow grain size distribution as illustrated in
FIG. 1 was obtained. - A submicron WC-10% Co-0.2% V cemented carbide was made in the following way according to the invention: 4.4 g ammonium vanadate (NH4VO3) was dissolved in 100 ml water and 900 ml ethanol (C2H5OH). To this solution was added 1000 g tungsten trioxide (WO3) The milling was carried out in a 2.4 litre ball mill with 1000 g milling balls and the milling time was 120 minutes. All other steps was made in the same way as in Example 1. A dense cemented carbide structure with porosity A00 and hardness HV3=1680 was obtained. A submicron microstructure with a narrow grain size distribution similar to
FIG. 1 was obtained. - A WC-10% Co-0.4% Cr cemented carbide was made in the following way according to patent U.S. Pat. No. 5,993,730: 23 g chromium (III)nitrate-9-hydrate (Cr(NO3)3×9H2O) was dissolved in 1700 ml methanol (CH3OH). To this solution, 105 g triethanolamine ((C2H5O)3N) was added during stirring. After that 686 g hexagonal WC (dWC=0.6 μm) was added and the temperature was increased to about 70° C. Careful stirring took place continuously during the time the methanol was evaporating until the mixture had become viscous. The dough-like mixture was worked and crushed with a light pressure when it had become almost dry.
- The powder obtained was fired in a furnace in a porous bed about 1 cm thick in nitrogen atmosphere in a closed vessel, heating rate 10° C./min to 550° C., completed with reduction in hydrogen for 90 minutes, finally followed by cooling in hydrogen atmosphere at 10° C./min. No cooling step between burning off and reduction step was used.
- The powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys. A dense cemented carbide structure with porosity A00 and hardness HV3=1670 was obtained. A submicron microstructure with about the same mean grain size but a somewhat broader grain size distribution compared to
FIG. 1 as illustrated inFIG. 2 was obtained. - A WC-10% Co-0.4% Cr cemented carbide was made in the following way according to JP-A-10-212165: 2.7 g chromium trioxide (Cr2O3) was mixed up with 500 g tungsten trioxide (WO3). The mixing was carried out in a 2.4 litre ball mill with 500 g milling balls and the milling time was 120 minutes.
- The powder mixture was fired in a continues laboratory reduction furnace in a porous bed about 2 mm thick in dry hydrogen atmosphere (dew point <−60° C.), heating rate about 30° C./min, reduction in hydrogen for 115 minutes at 700° C. completed by further reduction for 115 minutes at 900° C., finally followed by cooling in hydrogen atmosphere at about 30° C./min.
- The tungsten powder obtained was mixed with carbon black to over-stoichiometric composition (6.25 weight-% C) and homogenized in a 2.4 litre ball mill. Ratio milling balls to powder weight: 1/1.
- Milling time: 180 min. The powder mixture was burnt off in hydrogen atmosphere in a laboratory carburizing furnace at 1350° C. for 150 minutes. Heating rate: 30° C./min and cooling rate: 45° C./min.
- The powder obtained was mixed with pressing agent and Co-binder (Co-powder extra fine) in ethanol and adjustment of carbon content (carbon black), dried, compacted and sintered according to standard practice for WC-Co alloys. A dense cemented carbide structure with porosity A00 and hardness HV3=1620 was obtained. A submicron microstructure with about the same mean grain size but broader grain size distribution compared to FIGS. 1 to 2 as illustrated in
FIG. 3 was obtained. - The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention, which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
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SE0302199A SE526626C2 (en) | 2003-08-12 | 2003-08-12 | Ways to manufacture submicron cemented carbide |
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Cited By (3)
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CN108892141A (en) * | 2018-09-06 | 2018-11-27 | 北京科技大学 | A kind of high-purity, ultrafine tungsten carbide preparation method |
CN113939474A (en) * | 2019-05-13 | 2022-01-14 | 住友电气工业株式会社 | Tungsten carbide powder and method for producing same |
US11339096B1 (en) | 2019-05-13 | 2022-05-24 | Sumitomo Electric Industries, Ltd. | Tungsten carbide powder |
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RU2452784C1 (en) * | 2011-04-18 | 2012-06-10 | Государственное образовательное учреждение высшего профессионального образования "Тихоокеанский государственный университет" | Method of producing fine tungsten carbide powder |
CN110142414A (en) * | 2019-06-25 | 2019-08-20 | 赵立夫 | A kind of preparation method of nanocrystalline NC cutting tool hard alloy compound powder |
WO2024005100A1 (en) * | 2022-06-30 | 2024-01-04 | 京セラ株式会社 | Tungsten carbide powder |
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JP4489042B2 (en) * | 2006-03-20 | 2010-06-23 | 株式会社東芝 | Method for producing sintered body for cutting tool |
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- 2004-05-21 EP EP04012010A patent/EP1507014A1/en not_active Withdrawn
- 2004-06-29 KR KR1020040049611A patent/KR101139745B1/en not_active IP Right Cessation
- 2004-08-03 CN CN2004100588857A patent/CN1584093B/en not_active Expired - Fee Related
- 2004-08-11 JP JP2004234454A patent/JP2005060224A/en active Pending
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US4008090A (en) * | 1971-09-09 | 1977-02-15 | Sumitomo Electric Industries, Ltd. | Process for the production of tungsten carbide or mixed metal carbides |
US5567662A (en) * | 1994-02-15 | 1996-10-22 | The Dow Chemical Company | Method of making metallic carbide powders |
US5993730A (en) * | 1997-10-14 | 1999-11-30 | Sandvik Ab | Method of making metal composite materials |
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CN108892141A (en) * | 2018-09-06 | 2018-11-27 | 北京科技大学 | A kind of high-purity, ultrafine tungsten carbide preparation method |
CN113939474A (en) * | 2019-05-13 | 2022-01-14 | 住友电气工业株式会社 | Tungsten carbide powder and method for producing same |
US11339096B1 (en) | 2019-05-13 | 2022-05-24 | Sumitomo Electric Industries, Ltd. | Tungsten carbide powder |
US11396451B2 (en) | 2019-05-13 | 2022-07-26 | Sumitomo Electric Industries, Ltd. | Tungsten carbide powder and production method therefor |
Also Published As
Publication number | Publication date |
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JP2005060224A (en) | 2005-03-10 |
KR101139745B1 (en) | 2012-04-26 |
SE0302199L (en) | 2005-02-13 |
CN1584093B (en) | 2012-06-27 |
EP1507014A1 (en) | 2005-02-16 |
CN1584093A (en) | 2005-02-23 |
KR20050018588A (en) | 2005-02-23 |
US7514061B2 (en) | 2009-04-07 |
SE0302199D0 (en) | 2003-08-12 |
SE526626C2 (en) | 2005-10-18 |
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